Generally, Universal Serial Bus (USB) is a serial bus standard to the Personal Computer (PC) architecture with a focus on computer interface, consumer and productivity applications. The existing Universal Serial Bus (USB) interconnects have the attributes of plug-and-play and ease of use by end users. Now, as technology innovation marches forward, new kinds of devices, media formats and large inexpensive storage are converging. These devices require significantly more bus bandwidth to maintain the interactive experience that users have come to expect. In addition, the demand of a higher performance between the PC and increasingly sophisticated peripherals is increasing. The transmission rate of USB 2.0 is insufficient. As a consequence, faster serial bus interfaces such as USB 3.0, have been developed, which may provide a higher transmission rate so as to satisfy the need of a variety devices.
Electronic devices, such as personal mobile devices, tablet computers, etc., have become lighter, thinner, shorter, and smaller. In order to reduce the size of the electronic device, the electrical receptacle connector assembled to the electronic device needs to be small and precise. Normally, the electronic device has a standardized connector interface such as a Micro USB electrical receptacle connector adapted to be mated with a Micro USB electrical plug connector for power or signal transmission.
A conventional Micro USB electrical plug connector comprises a plastic core, a plurality of terminals, an upper shell, and a lower shell. The plastic core has a base portion and a tongue portion extended from the base portion. The terminals are held in the base portion, one end of each of the terminals is located at the surface of the tongue portion, and the other end of each of the terminals is protruded from the base portion and soldered with a circuit board. The upper shell and the lower shell are combined with each other to enclose the base portion and the circuit board. However, the upper shell and the lower shell provide functionality for covering the circuit board, but not positioning the circuit board. In addition, the lower shell defines grooves at two sides for assembling the circuit board. When the circuit board is assembled into the grooves, the lower shell may be deformed or bent easily because the lower shell is devoid of strengthening structures.